Improvement in mariners  compasses



v 2SheetsSheet1. J'; MONA-BB.

MARINERS commas. No.177,869. Patented May 23,1876.

F1434. 2 P s s @itnesses A ll arney.

N.FETER5, FHOTO-LITHDGRAFHER. WASHINGTON. D. C

J. MONABB, MARINERS COMPASS.

Patented my 23,1876.

m m m N-PBERS, PHOimLITHOGRAPHER. WASHINGTON. D Q

UNITED STATES PATENT OFFIcE.

JAMES MCNABB, OF WIDDER, CANADA.

IMPROVEMENT m MARINERS COMPA Specification forming ofIZet ters'Patent No. 1 77,869, dated May 23, 1876; application filed February 14,1876.

To all whom it may concern Be it known that I, J AMES MGNABB, of Widder, Lambton county, Ontario, inthe Domin ion of Canada, have invented certain Improvethe card being removed. Fig. 2 is a plan of one-half the card; Fig. 3, a vertical section of the card and of the needles; Fig. 4, a vertical section, on the line 00 y, of the compass, embracing my said improvements, omitting the gimbal. Figs. 5 and 6 are, respectively, vertical and horizontal sectional views of the tube 73, shaft h, and friction-rollers around said shaft, on an enlarged scale. section of the feather f. Fig.8 is a side elevation of the joint q r s f a, Fig. 1, represents the bowl of the compass; b, the gimbal; 0, Fig. 4, the center-pin, all of which are of ordinary construction. d and e, the horns of the bowl, are tubular. f, Fig. 4, is a feather or blade (shown in two positions) connected freely by a stirrup, g, and pivot to a vertical shaft, h, which passes through a tube, '5, extending from the deck j through the bottom of the vessel, marked j, Fig. 4. k and 1, Figs. 4, 5, and 6, are friction-rollers surrounding the shaft h at its upper and lower ends. These rollers have bearin gs in the collars 71. and h respectively. The flat faces of the rollers in the collar h travel on the head of the tube 03, their edges being in contact with the curb h. The shaft is thus supportedon the tube 6 by means of the collar W. m, Figs. 1 and 4, is a short arm rigidly attached to the upper end of the shaft h. n, -Fig. 1, is a link connecting the arm m with the lever 0, which is pivoted to a spur, p, proceeding from the binnacle, (a portion of which is shown in section.)

The lever o is flexibly attached to one end of the sliding rod q, Fig. 1, which is forked, and which carries the slotted segment 1", the forks of said rod embracing the gimbal-pin, all as shown in Figs. 1 and 8. s, Fig. 1, is a forked sliding rod, which is provided with a spur, t,

Fig. 7 is a transverse which slides in theslot of the segment 1', the

joint, with the rod 12, Figs. 1 and 4, which slides through the tubular horn e of the bowl, and is attached, at its inner end, by a swivel, to

the frame w, which, by a link, a, is attached" to the nonius-frame b which swings upon the center-pin by sleeves c and d, Fig. 4. e and f, Fig. 1, are the gimbal-horns, which have hearings in the binnacle, as usual.

The system of levers and connections above described are necessary to convey the motion communicated by the feather f of the shaft h to the nonius 9 without communicating to the compass any motion due to the motion of the vessel.

The feather at all times corresponds with the course the vessel is making, and governs the nonius, so as to indicate to the mariner the leeway of the vessel. The feather is shown by dotted lines in the position it holds when the vessel is not moving. When necessary, on account of the shallowness of the water, or for any other reason, the shaft 71 and the feather f may be drawn up into the tube 11, out of the way of danger.

h and 6, Figs. 3 and 4, are the needles. They are placed at the south side of the card j in line, and, preferably, with a space intervening between them, as shown. The posi tive poles of the needles point directly to the center-pin, and when thus constructed and arranged they are beyond the influence of local attraction.

Instead of employing two needles arranged in line, (each needle consisting of a single bar, as set forth,) any number of such needles so arranged, or a single needle consisting of a single bar, or a single needle composed of anumber of separate thin plates or leaves placed side by side, in the usual way, may be employed, or two or any number of needles, each composed of separate leaves, as last mentioned, (said needles being arranged in line, as aforesaid,) may be employed, provided, in each instance, the needles or needle employed be located directly south'of the center-pin and at right angles to the east and west lineof the card.

and show her true course, substantially as set forth.

2. The combination, with the card, of one or more magnetic-needles arranged south of the center-pin, and at right angles to the east and west line of the card, for the purpose of neutralizing the influence of local attraction, substantially asset forth.

JAMES MCNABB.

Witnesses:

H. F. HOWELL, THos. A. BARTT. 

